@import './variable.styl'
// 背景图
bgImg(url, type)
  background url(url) no-repeat center center
  background-size type
// 定位
positCenter(left, top, bottom, right, x, y)
  position absolute
  left left
  top top
  bottom bottom
  right right
  transform translate(x, y)
// 默认基准 根据设计稿为准
$baseFontSize = 37.5
rem(px)
  return px / $baseFontSize * 1rem